1. Field of the Invention
This invention broadly concerns a multiple dosage syringe for administering selectable amounts of medication through a cannula. More particularly, the invention hereof permits the user to position the syringe in place before triggering the syringe to self-penetrate the skin and inject the medication.
2. Description of the Prior Art
Male impotence is a problem which is more often encountered upon aging, with geriatric patients comprising a significant if not majority of the patients. The treatment of male impotence has heretofore involved three principle areas other than psychiatric intervention. One method of treatment has involved penile implants. These have met with increased patient and physician resistance due to occasional rejection by the patient's body, the possibility of infection, and the need for the passage of a tube through the patient's skin on a permanent basis, coupled with the possibility of rupture of the implant. Another type of treatment which has been employed is vacuum therapy, where the patient places his penis in a tube and withdraws air to create a vacuum. The vacuum causes blood to flow into the penis and once rigidity is attained, a constrictor ring is placed around the penis to maintain rigidity until intercourse is complete. However, the vacuum devices may be bulky and the constriction rings uncomfortable, coupled with their tourniquet-like effects which require removal after a short period.
A third type of treatment being employed on a limited basis involves injection of a vasodilator such as Prostaglandin sold by The Upjohn Company, into the penis prior to intercourse to induce engorgement of the penis with blood. This method, described in U.S. Pat. No. 4,127,118 to Latorre, is gaining popularity, but presents two distinct disadvantages. One is the necessity for datermining a desired dosage for each patient. Because the patients differ in weight, the amount of vasodilator to be injected is variable, and often individual syringes must be preloaded by a physician or pharmacist prior to use. The physical ability and memory of a patient often makes it difficult for each patient to load his own syringe from a more economical vial. The second problem involves the difficulty of the patient in selecting the correct location for injection of the vasodilator into the flaccid penis, coupled with the reluctance of the patient to physically insert the needle or cannula through the skin and into the penis.
It is thus an object of this invention to provide a syringe which is capable of injecting multiple doses of a medication.
It is another object of this invention to provide a syringe with an auto-inject feature which will permit patient placement of the syringe without a projecting cannula.
It is another object of this invention to provide a syringe which will penetrate the patient's skin and inject a dose of medication in response to activation of a trigger mechanism.
It is another object of this invention to provide a syringe which will retract the needle after use.
it is another object of this invention to provide a syringe capable of adjustment to provide different dosages.
It is another object of this invention to provide a syringe which is provided with a tactile, positive indicator whereby the patient can readily ascertain when the syringe has been set for a predetermined dosage of medication.
It is a further object of the invention to provide a mechanism whereby the pharmacist or physician can set the tactile, positive indicator for one of a number of different dosages.
It is yet further object of the invention to provide a multiple dosage syringe having a compact and portable configuration which is easy to use for geriatric patients.